Telephone-exchange system



R. S. WILBUR.

TELEPHONE EXCHANGE SYSTEM.

APPHCATION FILED MAYZI, I919.

Patented 001 19,1920.

om n smrs? o RAY s. WILBUR, or nrnnrrunsr, new .iERsE-Y, ASSIGNOR ro wns'rnnn ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

To all whomitmag concern: a

Be it known that I, RAY S. WILBUR, a citizen of the United States, residing at Lyndhurst, in the county of Bergen, State of New Jersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems of the central energy type in which the source of ringing current is automatically connected to and disconnected from a telephone line.

An object of this invention is the production of improved signaling means for systerns of this character in which the signal 'control apparatus functions independently of the length of the telephone lines to which signaling current may be connected.

In attaining this object of the present in-' vention, there is provided at the central ofiice, means for connecting the source of signaling current with a telephone line, a relay energized by current from the source for maintaining the source connected therewith and a relay energized in response to the subsequent closure of the telephone line for disconnecting the source therefrom.

A more complete understanding of the invention may be had from the following description taken in conjunction with the accompanying drawing which forms a part thereof. A

Figure 1 shows a trunk circuit illustrating one embodiment of the invention; and Fig. 2 illustrates a second embodiment of the invention as applied to a cord circuit.

Referring now to the drawing, there is shown in Fig. 1 a trunk circuit A extending from a switchboard X toa switchboard Y. The portion of the apparatus to the left of the dotted line 22 is associated with the switchboard at X, while that to the right thereof is associated with the switchboard at Y. In Fig. 2 there is shown the callingend' of a cord circuit D together with the derstood after considering the following de scription.

pleting a connection with the telephonev linev Oa'nd'thatthe operator at X has inserted plug 5 ofa cord circuit within jack 6. Relay 7 thereupon operates over a circuit ex tending from battery (not shown) in the cord circuit at position X throughthe ring contacts of the plug-5 and the j aok 6, winding 8 of repeating coil-9,the'right-hand winding of relay 7, winding 10 of repeating coil 9, tip contacts of the jack 6 and the plug 5 and over the tip conductor of the con nected cord circuit to ground. Relay 7 in operating causes the operation of relay 11 over a circuit extending from battery through the winding of relay 11 and the contact of relay 7 to ground. The operation of relay 11 causes the illumination of supervisory lamp 12 over a circuit extending from battery through the lamp 152, right-hand alternate contact of relay 11 and normal contact of relay 13 to ground,which serves as an indication to the operator at A that connection has been completed with the assigned'trunk. 1 1

I The operator, having been advised that connection is "desired with the line of subscriber C, inserts plug 1 1 of the trunk circuit A into jack 15 of the telephone line, causing the operation of relay 13 and cut' off relay 16 over a circuit from battery through the winding of relay 13, sleeve con tacts of the plug 14 and the jack 15 and the winding of relay 16 to ground. Thecut-ofi 20, left-hand alternate contact of relay 11 and the alternate contact of relay 13' to ground. Relay 19in operating causes the energi'zation of relay 20 over a circuit from battery through the'winding of relay 20, an upper alternate contact of ringing relay 19, normal contact of relay20, left-hand alternate contact of relay 21 and the alternate contact of relay 13 to ground. Relay 20 in Specification of Letters Patent. Patent d Ot 19 1920 7 Application filed my 21, 1919.. Serial No. 298,624.

operating locks up through its alternate contact and transfers the holding circuit of relay 19 to the normal contact 24 of relay 21.

The operation of ringing relay 19 connects a source of ringing current to the called for line over a circuit extending from the source thereof through a lower alternate contact of ringing relay 19, winding of relay 22, condenser 23, an upper alternate contact of ringing relay 19, tip contacts of the plug 14 and the jack 15, out over oneside of the line, through the usual call bell at the station C, back over the other side of the line, ring contacts of the jack 15 and the plug 14. and a lower alternate contact of ringing relay 19 to ground. Condenser 23 prevents the flow of direct current through the winding of relay 22. Ringing current also traverses the winding of relay 21, which, with respect to the source of'ringing current, is connected in parallel with the line. The armatures of the relays 21 and 22 are connected together and are held in their normal unactuated position by means of a retractile spring 44. -The adjustment of these connected armatures with respect to the pole faces of the relays 21 and 22 is such that when the windings of both are traversed by ringing current only, as before the closure of the switchhook contacts at the called station, the relay 22 exerts a much greater pull upon the armatures than is exerted by the relay 21. However, when the winding of relay 21 is also traversed by direct current, the relay 21 then exerts a greater pull upon the armatures than is exerted by the realy 22.

The party at station C in answering the call by removing the receiver from the switchhook closes the contacts thereof, thereby causing the operation of relay 21 over a circuit from battery through the winding of relay 21, an upper alternate contact of relay 19, tip contactsof the plug 14 and the jack 15, through the contacts of the switchhook at station O, ring contacts of the jack 15 and the plug 14, and a lower alternate contact of relay 19 to ground. Relay 21 is so designed that when the energizing circuit therefor is completed it posseses sufficient magnetizing force or pull to overcome that exerted by relay 22 on the rigidly connected armatures. The operation of relay 21 thereby opens its normally closed contact 24 which opens the holding circuit for ringing relay 19, causing the release thereof.

and the disconnection of the ringing current from the line.

Upon the release of ringing relay 19, su pervisory relay 25 operates over a circuit from battery through the winding of relay 25, lower normal contact of relay 19, ring contacts of the plug 14 and the jack 15, out over one side of the line, contacts of. the switchhook, back over the other side of the line, tip contacts of the jack 15 and the plug 14 and an upper normal contact of relay 19 to ground. Relay 25 in operating con nects the low resistance left-hand winding of relay 7 in parallel with the high resistance right-hand winding thereof, thereby reducing the resistance in circuit with the calling supervisory relay (not shown) of the connected cord circuit premitting the operationof this relay. The operation of this supervisory relay extinguishes the supervisory lamp controlled thereby, which is an indication to the operator that the called party has responded.

It is thereby evident from the above description that the disconnection of ringing current from the line is controlled entirely through the contacts of the switchhook. The ringing current will, however, be connected to the line as long as such contacts are maintained open, since the armatures controlled by relays 21 and 22 are rigidly connected together, thereby maintaining the energizing circuit of the ringing relay 19 closed until a path for direct current through the winding of relay 21 is established, which is not effective until the subscriber answers. Since ringing current traverses the windings of both of the relays 21 and 22, it will be seen that variations in length of line will have but little effect upon both relays and the increase of current through the winding of relay 21, due to an increase of impedance when the line is lengthened will not be sufficient to cause it to exert a greater pull on the armatures than is exerted by relay 22 while ringing current only is traversing the windings of both. Therefore, the possibility of premature disconnection of ringing current from the line is eliminated.

Referring to Fig. 2, there is shown a portion of a long line circuit terminating in the jack 26, with which the cord circuit 1) (only a portion of which is shown) is adapted to be connected. The cord circuit D is equipped for automatic ringing while the long line circuit is provided with improved means for maintaining the ringing current connected thereto, as long as the line is open and disconnecting the same upon the closure of the line.

Referring to the operation of the system shown in Fig. 2, the insertion of the plug 27 of the cord circuit D into the jack 26 of the line E causes the operation of relay 28 and illumination of the lamp 29 over a circuit from battery through the lamp 29, winding of relay 28, sleeve contacts of the plug 27 and the jack 26 to ground. The operation of relay 28 causes the energization of ringing relay 31 over a circuit from battery through resistance 30, winding of ringing relay 31, normal contacts of relays 32 and 33, and the contact. of relay 28 to ground. Ringing relay 31 upon being energized connects a source of'ringing current to the line over a c1rcu1t from the source through the winding of tripping relay 33,

lower alternate contact of ringing relay 31, ring contacts of the plug 27 and the jack 26, out over line wire 42, through the call bell at the station (not shown), back over line wire 43, tip contacts of the jack 26 and the plug 27 and the upper alternate contact of relay 31 to ground. Ringing currentalso traverses the windings of relays and 37 but the adjustment of the armatures thereof, which are rigidly connected together, with respect to the pole faces of these relays is such that when ringing current traverses the windings of both relays before the closure of the telephone line, relay 35 exerts a greater pull upon the armatures than is exerted by relay 37 The rigidly connected armatures are held in their normal unactuated osition by means of a retractile spring 45. owever, upon the closure of the telephone line, as when the receiver is removed.

from its switchhook, a path for directcurrent is established including the windings of relay 37, which will thereupon exert a much greater pull on the rigidly connected armatures than is exerted by relay 35.

The called subscriber in responding to the operation of the call bell removes the receiver from the switchhook establishing the path for direct current, including the windings of relay 37. Relay 37 now exerts a much greater pull on the rigidly connected armatures than is exerted by relay 35, thereby closing contact 38 which connects the impedance coil 36 in bridge of the telephone line.

The connection of the impedance coil 36 in bridge of the telephone line causes the operation of the tripping relay33 which removes the short circuit from about the winding of relay 32. Relay 32 thereupon operates opening another contact in the normal short circuit of its own winding, and establishing at its alternate contact a short circuit for the winding of ringing relay 31,

causing the release thereof and the disconnection of the source of ringing current from theline. Supervisory relay 40 now operates over a circuit from battery through the lower right-hand winding of repeating coil 41, winding of supervisory relay 4L0,

lower normal contact of ringing relay 31,

ring contacts of the plug 27 and the jack 26, impedance coil 36, contact 38, tip contacts of the jack 26 and the plug 27, the upper normal contact of relay 31 and the upper right-hand winding of the repeating coil ll to ground. Supervisory relay 40 in operating connects resistance 30 in shunt of the supervisory lamp 29, which is thereby extinguished.

What is claimed is: e

1. A telephone exchange system comprissignaling current connected with the line until the closure thereof.

2. A telephone exchange system comprising a telephone line, a source of signaling current, a link circuit, a ringing relay in the link circuit responsive to the connection thereof with the telephone line for connecting'said source of signaling current to the line, and a relay initially energized by current from said source for maintaining the source of signaling current connected with the line until the closure thereof.

3. A telephone exchange system comprising a telephone line, a link circuit, a source of ringing current, a ringin relay energized upon the connection oftfie with the line to connect the source of ringing current with the line, a relay energized by ringing current to maintain the ringing relay energized, and a third relayenergized upon the removal of the receiver from its switchhook to cause the release of the ringing relay.

4:. A telephone exchange system compris ing a telephone line, a link circuit, a source of ringing current, a ringing relay in the link circuit for connecting ringing current to the line; an impedance coil, a relay energized by current from said source to main tain the ringing relay energized, and means operative upon the closure of the telephone line to connect said impedance coil in bridge of the telephone line, thereby causing the release of the ringing relay to disconnect the source of ringing current from the line.

5. A telephone exchange system comprising a telephone line, a link circuit, a source of signaling current, a relayin the link circuit for connecting the source of signaling current with the line, means operated by current from said source to maintain the source of signaling current connectedto the telephone line while open, and a second means operative upon the closure of the telephone line to cause the release of the link circuit 1 ringing relay to disconnect the source of.

line to cause the release of said first mentioned relay to disconnect the source of signaling current from the line.

7. In a telephone exchange system, in combination, a telephone line, a source of signaling current, means for connecting the source of signaling current with the telephone line, a relay energized by current from said source for maintaining the source connected with the telephone line, and a relay energized in response to the closure of the telephone line for causing the disconnection of the source therefrom.

In witness whereof, I hereunto subscribe my name this 15th da of May A. D., 1919.

IXAY S. WILBUR. 

